Method and apparatus for removing water vapor as a byproduct of chemical reaction in a wafer processing chamber

ABSTRACT

A system, apparatus and/or method is provided for removing water vapor from a wafer processing chamber generated as a byproduct of wafer processing. A water vapor trap is used to collect the water vapor byproduct from the processing chamber interior. The water vapor trap has at least a portion thereof in communication with an interior of the processing chamber for collection of the water vapor and another portion thereof in communication with an exterior of the processing chamber. The portions are movable with respect to the interior and exterior of the processing chamber such that the portions may switch places. This allows the processing chamber to be in at least a substantially continuous mode of operation while still providing for the removal of water vapor byproduct via the water vapor trap. The “used” portion of the water vapor trap is regenerated while the “clean” portion is collecting water vapor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to the manufacture of semiconductordevices and, more particularly, to wafer fabrication and/or processing.

2. Description of the Art

The manufacture of semiconductor wafers to create semiconductorintegrated circuit devices typically involves a sequence of processingsteps that fabricate the multi-layer structure generally associated withthe integrated circuit devices. Such processing steps may include (1)the deposition of metals, dielectrics, and semiconductor films, (2) thecreation of masks by lithography techniques, (3) the doping ofsemiconductor layers by diffusion or implantation, (4) the polishing ofouter layers (e.g. chemical-mechanical polishing), and (5) the etchingof layers for selective or blanket material removal.

Semiconductor integrated circuits are typically fabricated by a layeringprocess in which several layers of material are applied on or in asurface of a wafer, or on a surface of a previous layer. These layerscan constitute a metal pattern forming various elements of an electricalcircuit. Insulating material and dielectric material are added atvarious stages of the fabrication process. The layers are typicallytreated to create a smooth, planar surface. In addition to the surfacecharacteristics, the thickness of the thin film layers can be criticalto the performance of a semiconductor and/or its circuit components. Forexample, the performance characteristics of a particular circuit elementmay be affected, usually detrimentally, by a dielectric film thickness.

In forming a semiconductor device, one common practice has been to usedeposition techniques to apply a particular layer to an existingsubstrate or layer. In one type of process, a vapor deposition tubesprays a vapor including the layer material onto the workpiece (i.e.semiconductor wafer). In a typical vapor deposition process, thethickness of the thin film layer is measured following completion of thedeposition. Under these circumstances, the film thickness is generallycontrolled by the amount of time that the device is exposed to the vapordeposition process. The subsequent measurement of the film thickness isoften accomplished in a “go/no-go” manner in which devices having a filmthickness falling outside a predetermined thickness range are rejectedand scrapped. In other cases, the semiconductor device is returned forfurther processing, either for additional material deposition, or formaterial removal such as in a polishing process. Ordinarily, theeconomics of mass production mitigate in favor of simply scrapping thecomponent.

Wafer processing such as that described above is typically accomplishedin a wafer processing chamber. An exemplary wafer processing chamber hasa processing head that introduces a gas or gasses into the processingchamber. A bias voltage may or may not be applied to the processinghead. The wafer processing chamber also includes other components forprocessing the wafer. It is generally necessary to maintain relativelyprecise control of various parameters such as the temperature of asemiconductor wafer during performance of certain of the processingsteps associated with manufacture of the wafer. For example, a number ofprocessing steps associated with wafer fabrication involve complexchemical reactions that require the temperature of the semiconductorwafer to be controlled within predetermined specifications.

In some types of wafer fabrication water is a byproduct of the reaction.Particularly, in wafer fabrication with respect to low k films, water isa major byproduct of the reaction. Additionally, it is desirable toremove as much of the water vapor as the system will allow. The mainmethod for accomplishing water vapor removal is to increase the pumpingspeeds of the systems vacuum pumps. A problem with this method is thatby increasing the pumping speeds to remove unwanted water vapor, othergases needed for processing are removed.

One way to improve the pumping speed is to use a form of Meissner trap.A Meissner trap will freeze the water in the chamber, improving thequality of the film. A Meissner trap will greatly reduce the particlepressure of water vapor in a processing chamber without changing theother gasses being used in the particular process.

The above systems utilize a Meissner or cold trap to improve the abilityto pump down (evacuate or reduce the pressure of) the processingchamber. Particularly, the cold trap is used to improve the ability ofthe processing chamber to pump down quickly to a base pressure neededfor wafer processing. A problem with these systems is that they utilizefull cryo-pumps that operate at very low temperatures. Another method toremove water vapor is to increase the pump speed and/or pump volume.While increasing the pump speed and/or volume may work to remove morewater vapor, such will also remove the beneficial gas or gasses fromwithin the processing chamber. This would then make the system providemore processing gas than necessary.

What is needed in view of the above, is a method of and/or apparatus forremoving water vapor from a wafer processing chamber during waferfabrication.

What is further needed in view of the above is a method of and/orapparatus for removing water vapor from a wafer processing chamber, thewater vapor being a byproduct of wafer processing.

What is even further needed in view of the above, is a method of and/orapparatus for substantially continuously removing water vapor from asubstantially continuously operating wafer processing chamber, the watervapor being a byproduct of wafer processing.

SUMMARY OF THE INVENTION

The subject invention is a process and apparatus for removing watervapor from within a wafer processing chamber, the water vapor generatedas a byproduct of wafer processing and/or as a constituent of backgroundgases. Preferably, water vapor removal is accomplished essentiallycontinuously during wafer processing.

In one form, there is provided a method of operating a wafer processingchamber, the wafer processing chamber defining an interior and having aprocessing head in the interior and in communication with a processinggas, a wafer holder in the interior and adapted to receive a wafer forprocessing, and a pumping port in communication with the interior and apump. The method of operating the wafer processing chamber includes thesteps of: (a) providing a water vapor accumulator having at least aportion thereof in communication with the interior of the processingchamber; (b) cooling the portion of the water vapor accumulator incommunication with the interior of the processing chamber to a watervapor condensation temperature; (c) processing a wafer supported on thewafer holder utilizing the process gas, the wafer processing generatingwater vapor as a byproduct; and (d) accumulating the generated watervapor on the portion of the water vapor accumulator in communicationwith the interior of the processing chamber.

In another form, there is provided a method of wafer processing. Themethod includes the steps of: (a) placing a first surface of a watervapor trap in communication with an interior of the wafer processingchamber; (b) cooling the first surface to a water vapor condensationtemperature; (c) processing a wafer in a wafer processing chamber usinga processing gas, the wafer processing producing water vapor as abyproduct; (d) accumulating the byproduct water vapor on the firstcooled surface; (e) moving the first cooled surface from communicationwith the interior of the wafer processing chamber to a position exteriorto the interior of the wafer processing chamber; (f) moving a secondsurface of the water vapor trap in communication with the interior ofthe wafer-processing chamber; and (g) cooling the second surface to thewater vapor condensation temperature.

In yet another form, there is provided a system for processing a wafer.The system includes a processing chamber, a processing head disposed inthe processing chamber and in communication with a source of processinggas, a vacuum port in the processing chamber and in communication with avacuum source, a wafer holder in the processing chamber and configuredto releasably receive a wafer for processing; and a water vapor trap atleast partially disposed in the processing chamber. The water vapor trapis operative to cool a first surface of the water vapor trap to a watervapor condensation temperature during wafer processing, to accumulatewater vapor generated as a byproduct result of wafer processingutilizing the processing gas and condensed thereon, move the firstsurface out from the Interior, and position a second surface of thewater vapor trap into communication with the interior, the water vaportrap further operative to cool the second surface to the water vaporcondensation temperature during wafer processing and to accumulate thegenerated byproduct result of wafer processing.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention will be better understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a block diagram of an exemplary apparatus for processing waferin accordance with the principles of the subject invention;

FIG. 2 is a block diagram of an exemplary apparatus for processing awafer in accordance with the principles of the subject invention;

FIG. 3 is a block diagram of an exemplary cooling system for theexemplary wafer processing apparatus of FIGS. 1 and 2;

FIG. 4 is a block diagram of another exemplary cooling system for theexemplary wafer processing apparatus of FIGS. 1 and 2;

FIG. 5 is a perspective view of an exemplary wafer processing apparatusin accordance with the principles of the subject invention;

FIG. 6 is a perspective view of the exemplary wafer processing apparatusof FIG. 5 illustrating production of water vapor during wafer processingand collection of the water vapor by a water vapor trap in accordancewith the principles of the subject invention;

FIG. 7 is a perspective view of the exemplary wafer processing apparatusof FIGS. 5 and 6 illustrating a manner of removing the collected watervapor; and

FIG. 8 is a flowchart depicting an exemplary process for removing watervapor from a wafer processing chamber generated as a byproduct of waferprocessing.

Corresponding reference characters indicate corresponding partsthroughout the several views.

DETAILED DESCRIPTION OF THE INVENTION

With reference now to FIG. 1, there is shown a block diagram of anexemplary environment, generally designated 10, for processing a waferin accordance with the subject principles. The exemplary environment 10may be embodied as a wafer processing system and/or apparatus. The waferprocessing system 10 includes a processing chamber, enclosure, or thelike (collectively, chamber) 12 fabricated from a material such as ametal that is suitable for various types of wafer fabrication. Waferfabrication may include, without being limiting, etching, CVD, ASH, orany other type of wafer processing as is known in the art. Theprocessing chamber 12 encloses a processing head 14 and a wafer holderor chuck 30. The processing head 14 is in communication with a gas orvarious gases, represented by gas inlet 16, each one of which or acombination thereof being suitable for the type of wafer processingbeing performed. The gas inlet 16 is shown coupled topipes/inlets/valves 18, 20, and 22 representing one or a plurality ofregulated and/or controlled gas source(s)/inlet(s). The processing head14 is configured, adapted, and/or operative to introduce a gas and/orgases as appropriate for the particular process being used on the wafer28.

The processing head 14 may also be in communication with a source ofelectricity represented by power port 24. The power port 24 is showncoupled to an incoming line 26, which in turn, is in communication witha source of electricity (not shown). The source of electricity providessuitable electrical power. Particularly, the source of electricityprovides a bias voltage for the processing head 14 should the processinghead 14 require a biasing voltage for the particular process beingperformed on the wafer 28 and/or in the processing chamber 12.

The processing chamber 12 has an opening, valve, door, or the like 32(labeled wafer “opening” in FIG. 1) that provides controlled and/orregulated ingress and egress of a wafer 28 into the processing chamber12. Particularly, the wafer opening 32 allows a wafer to placed into theprocessing chamber 12 and be received by the wafer holder 30. The waferopening 32 also allows the processed wafer 28 to be removed from thewafer holder 30/processing chamber 12. The wafer holder 30 preferablymoves in an appropriate and controlled and/or regulated manner to andfrom the wafer opening 32 to receive an unprocessed wafer and dispatch aprocessed wafer once processing is complete, rather than the wafer beingmoved onto the wafer holder 30. However, various other manners arecontemplated.

The processing chamber 12 also includes a pumping/vacuum port 34. Thepumping port 34 is in communication with a vacuum pump or source (notshown) that is represented by the valve/inlet 36. The processing chamber12, may be pumped out to achieve vacuum pressure(s) therein and/orpressures that are below normal atmospheric pressure. The pressure atwhich the processing chamber 12 is maintained by the vacuum pump via thevacuum port 36 depends on the particular process being performed on thewafer 28. Additionally, the speed at which a particular pressure isreached is dependent upon the vacuum pump.

In accordance with an aspect of the subject invention, a water vaportrap 38 is associated with the processing chamber 12. The water vaportrap 38 is configured, adapted and/or operative to trap and/oraccumulate water vapor that is within the processing chamber 12.Particularly, the water vapor trap 38 is configured, adapted and/oroperative to trap and/or accumulate water vapor that is generated and/orproduced as a byproduct of wafer processing. More particularly, thewater vapor trap 38 is configured, adapted and/or operative to trapand/or accumulate water vapor generated and/or produced as a byproductof wafer processing and allow removal of the trapped and/or accumulatedwater vapor. The water vapor trap 38 is further configured, adaptedand/or operative to remove the trapped and/or accumulated water vaporand/or have the trapped and/or accumulated water vapor removed therefromin a manner to allow the processing chamber to operate in a relativelycontinuous manner. The water vapor removal process may be termed“regening” wherein after the water vapor removal process, the watervapor trap and/or a portion of the water vapor trap may be termed“regened.”

The water vapor trap 38 operates and/or functions during waferprocessing to collect water/water vapor liberated, generated, and/orproduced as a result of and/or as a byproduct of wafer processing,particularly of the interaction of the gas or gasses with the wafer 28and/or substrate, coating or the like thereof. In one form, the watervapor trap 38 collects water/water vapor produced during waferprocessing up to a capacity of water vapor for the water vapor trap 38or a portion thereof and allows removal of the collected water/watervapor while the water vapor trap or another portion thereof permitsfurther collection of water/water vapor during further wafer processing(the same or different wafers). Water/water vapor removal in accordancewith the principles of the subject invention may be consideredcontinuous and/or cyclic.

In accordance with the operation and/or function thereof, the watervapor trap 38 is in communication with a water vapor trap control 50represented by the double-headed arrow therebetween. The water vaportrap control 50 is representative of control and/or regulation ofoperation and/or functionality of the water vapor trap 38. In one formas explained further below, this includes providing and/or controllingmovement of the water vapor trap 38 or a portion thereof. In anotherform as explained below, this includes supplying and/or regulatingcoolant to and for the water vapor trap 38. In a yet further form, thewater vapor trap control 50 may include control and/or regulation ofheat to and for the water vapor trap 38. The water vapor trap control 50may also be in communication with an external controller, processor,processing circuitry/logic and/or the like, as represented by thedouble-headed arrow emanating from the water vapor trap control 50 andthe processing chamber 12.

Referring now to FIG. 2, another exemplary embodiment of a waferprocessing system 10 is shown. In the wafer processing system 10 of FIG.2, the water vapor trap 38 includes a first surface 40 (Surface A) and asecond surface 42 (Surface B). It should be appreciated that thenomenclature “first” and “second” are arbitrary and thus can be reversedwithout consequence. As well, the surfaces 40 and 42 may constitutesides, walls, and/or the like, without limitation. Each surface 40 and42 preferably has a large surface area for collecting water vapor. Asillustrated in FIG. 2, one surface (surface A, 40) is internal or withinthe processing chamber 12, while another surface (surface B; 42) isexternal or outside the processing chamber 12. The water vapor trap 38of FIG. 2 is movable such that either one of the surfaces 40 and 42 maybe within or outside of the processing chamber 12. Movement may includerotation, pivoting, translation, or the like. When a surface is internalto the processing chamber 12, the surface is operative to collect watervapor. When a surface is external to the processing chamber 12 thesurface may be regened. In this manner, the water vapor trap may operateessentially continuously (i.e. the water vapor trap can be used tocollect water vapor during wafer processing while at the same timeremove or regen).

As depicted in FIG. 2, the processing chamber 12 is preferably disposedinside an enclosure 11. The enclosure 11 is in communication with thevacuum 34 such that the enclosure 11 is under the same vacuum conditionas the processing chamber 12. This allows the surface B (42) of thewater vapor trap 38 to vent within the enclosure 11 without venting theprocessing chamber 12 to atmosphere.

In one form, the water vapor trap 38 may be a thermal water vapor trapsuch as a cooling/cold object, cooling/cold trap, or the like. In thisform, the water vapor trap 38 or a portion thereof is reduced intemperature (i.e. cooled) to a temperature while within the processingchamber 12 appropriate to collect water vapor. Particularly, a surface40 of the water vapor trap 38 that is internal to the processing chamber12 is cooled to an appropriate temperature such that water vapor withinthe processing chamber 12 is caused to condense on the surface 40.Another surface 42 of the water vapor trap 38 is or may be external tothe processing chamber 12 for regeneration (water removal) while theother (or another in the case of a water vapor trap having more than twosurfaces) surface is internal to the processing chamber collecting watervapor. This is illustrated and/or represented in FIG. 2 by the watervapor control 50 including thermal, electrical and/or control lines 52,54 and 56. The thermal lines provide coolant, heat and/or electricityfor heat and operation of the mechanism to move the water vapor trap 38as necessary.

An appropriate temperature for the cooling object (the water vapor trap38 and/or a portion thereof) is 77K or higher. This can be achievedutilizing several methods. Referring to FIG. 3, an exemplary manner ofproviding a cooling object is illustrated as a system 60. The system 60includes the processing chamber 12 with the water vapor trap 38. Thewater vapor trap 38 is in communication with a coolant such as a liquidgas (e.g. LN2 or the like) 64 via valving/piping 62. The system 60depicted in FIG. 3 is a one-way system. Referring to FIG. 4, anotherexemplary manner of providing a cooling object is illustrated as asystem 70. The system 70 includes the processing chamber 12 and thewater vapor trap 38. The water vapor trap 38 is in communication with aclosed loop refrigeration system 76 via valving/piping 72 and 74. Thesystem 70 depicted in FIG. 4 is a two-way system. It should beappreciated that manner in which the water vapor trap 38 is cooled asdescribed above and/or depicted in FIGS. 3 and 4 are only exemplary anddo not limit the types of cooling systems that may be used.

Referring to FIG. 5, there is depicted a processing chamber 12 inaccordance with the principles of the subject invention. The processingchamber 12 includes the various components described above inconjunction with FIGS. 1 and 2. The processing chamber 12 is disposedwithin an interior 17 of the enclosure 11. The processing chamber 12includes a water vapor trap 38 that is embodied as a multi-surfaced andmovable (rotatable as represented by the axis of rotation arrow andcircular arrow) device 38. The water vapor trap 38 is maintained onand/or by a support 78. The support 78 includes tubing, piping, and/orthe like 79 that supplies the coolant, heat, electricity and/or controlsignals for the operation of the water vapor trap 38 (see item 50 inFIGS. 1 and 2).

In the example of FIG. 5, the water vapor trap 38 is a cooling/cooledobject that includes three sides, walls, or surfaces 80, 82, and 84. Inaccordance with one form of the subject invention, the water vapor trap38 is disposed outside the processing chamber 12 but inside theenclosure 11 and is operative to present one surface 80, 82 or 84 intothe processing chamber 12. In this embodiment, a wall 13 of theprocessing chamber 12 includes a cutout 15 essentially the same size asone of the surfaces 80, 82, and 84. Since the water vapor trap 38 isrotatable, the water vapor trap 38 is operative to present one surfaceat the cutout 15 such that the particular surface is exposed to theinterior of the processing chamber 12. A seal or the like may bepositioned about the cutout 15 and/or the surfaces 80, 82, and 84 of thewater vapor trap 38.

In FIG. 5, the surface 80 is presented at the cutout 15 and thus isdepicted as presenting itself to the interior of the processing chamber12. The surface 80 is caused to be cooled to around 77K or higher. Theother surfaces 82 and 84 are not cooled and one surface may be heated toremove any water vapor that has been collected thereon (particularly bycondensation). Referring to FIG. 6, the processing chamber 12 is shownduring a wafer processing mode. Particularly, gas is emanating from theprocessing head 14 as represented by the various arrows labeled “gas.”As well, water (H₂O) vapor is being produced as a byproduct of the waferprocessing as represented by the arrows labeled “H₂O.” As illustrated,the water vapor in the processing chamber 12 as a byproduct of waferprocessing, condenses on the surface 80 that has been appropriatelycooled. The surface 80 thus collects, traps, or accumulates the watervapor thereon. The parts of the water vapor trap 38 outside theprocessing chamber 12 (but inside the enclosure 11) are in the vacuum ofthe enclosure 11 so they can be vented, changed, regened, or the likewith very little impact to the processing chamber 12 and the processingoccurring therein.

In FIG. 7, the water vapor trap 38 has been rotated to present a cleanor regened surface (here surface 84) to the inside of the processingchamber 12. The surface 80 with a maximum amount of water vaporcondensed thereon is moved to the outside of the processing chamber 12.In this manner, wafer processing may continue while a surface of thewater vapor trap 38 may be regened. The processing chamber does not haveto shut down for the regen process. The water vapor shown condensed onthe surface 80 in FIG. 6 is shown as an outgas (not droplets) such thatthe water vapor can be exhausted therefrom.

The water vapor trap of FIGS. 5-7 has three surfaces or portions each ofwhich is separately cooled and heated. Each surface or portion is alsoseparately positionable in communication with or in the interior of theprocessing chamber and in communication with or in the exterior of theprocessing chamber. This may be accomplished by providing a temporaryand replaceable wall, side or other surface portion of the processingchamber as depicted in FIGS. 5-7. This may also be accomplished in othermanners such as by completely moving all or a portion of the water vaportrap into and out of the processing chamber.

It should be appreciated that the water vapor trap may be embodied as atwo-surface to a multi-surfaced object. As well, the water vapor trapmay move in any manner that allows a surface thereof to be presented tothe interior of the processing chamber and permits the surface to beremoved from the interior once “full.” Further, the water vapor trap maybe movable in any manner with respect to a surface or surfaces of thewater vapor trap or the water vapor trap itself.

FIG. 8 depicts a flowchart, generally designated 100, of an exemplarymanner of operation of the subject invention and reference is now madethereto. In step 102, a portion (or all depending on the particularembodiment of water vapor trap utilized) of the water vapor trap iscooled down to a temperature of approximately 77K or higher. In step104, wafer processing within the processing chamber may be started andstopped numerous times throughout and/or during the operation of thewater vapor trap as shown and described.

Proceeding, in step 106, water vapor within the processing chamber iscollected, trapped, accumulated, and/or the like on a portion of thewater vapor trap that is interior to the processing chamber. This isaccomplished by the water vapor condensing on the cooled portion of thewater vapor trap. In step 108, when the portion of the water vapor trapis “full”of condensed water vapor (i.e. its capacity is at a maximum orsooner if desired) the water vapor trap is adjusted (e.g. moved,rotated, etc.) to remove the “full” portion and replace it with a“clean” portion. In step 110, the “clean” portion is then cooled down toapproximately 77K or higher. The “clean” portion is then ready tocollect condensed water vapor as indicated in step 112.

In step 114, the “used” portion of the water vapor trap is thenregenerated (“regened”). This may be accomplished by heating up the usedportion to burn off the condensed water vapor. Once all of the condensedwater vapor has been removed, the portion is now “clean” and ready torepeat the process as indicated instep 116.

While this invention has been described as having a preferred designand/or configuration, the subject invention can be further modifiedwithin the spirit and scope of this disclosure. This application istherefore intended to cover any variations, uses, or adaptations of theinvention using its general principles. Further, this application isintended to cover such departures from the subject disclosure as comewithin known or customary practice in the art to which this inventionpertains and which fall within the limits of the appended claims.

What is claimed is:
 1. A method of wafer processing comprising the stepsof: placing a first surface of a water vapor trap in communication withan interior of the wafer processing chamber; cooling the first surfaceto a water vapor condensation temperature; processing a wafer in a waferprocessing chamber using a processing gas, the wafer processingproducing water vapor as a byproduct; accumulating the byproduct watervapor on the first cooled surface; moving the first cooled surface fromcommunication with the interior of the wafer processing chamber to aposition exterior to the interior of the wafer processing chamber;moving a second surface of the water vapor trap in communication withthe interior of the wafer processing chamber; and cooling the secondsurface to the water vapor condensation temperature.
 2. The method ofclaim 1, wherein the water vapor condensation temperature comprises atemperature no lower than approximately 77K.
 3. The method of claim 1,further comprising the step of: accumulating the byproduct water vaporon the second surface of the water vapor trap.
 4. The method of claim 1,wherein the steps of moving the first and second surfaces includesrotating the water vapor trap.
 5. The method of claim 1, furthercomprising the step of regenerating the first surface of the water vaportrap after moving the first surface from communication with the interiorof the water processing chamber to a position exterior to the interiorof the water processing chamber while the second surface of the watervapor trap is accumulating water vapor.
 6. The method of claim 5,wherein the step of regenerating the first surface of the water vaportrap includes heating the first surface.